Kolkata air quality still good, but will fall after lockdown is lifted: environmentalists

Air quality remained good across Kolkata on Wednesday, a week after cyclone Amphan lashed removing much of its green cover, but environmentalists warned that the quality will take a beating when the number of vehicles on the road will rise after the lockdown is lifted.

The Air Quality Index monitoring station at Ballygunje in south Kolkata recorded an AQI of 48 (PM 10) at 3 PM on Wednesday, which is 'good' in environmental parlance.

At the same time, readings at the AQI stations of Bidhannagar, Jadavpur, Fort William and Rabindra Sarobar were 41, 44, 47 and 20 respectively, an official of West Bengal Pollution Control Board said.

An AQI between 0 and 50 is considered 'good', 51-100 'satisfactory', 101-200 'moderately polluted', 201-300 'poor', 301-400 'very poor' and 401-500 'severe', while the AQI above 500 falls in the 'severe plus' category.

The official attributed the low AQI level to less number of vehicles on the road for the two-month-long lockdown period and the cleansing effect of cyclone Amphan and accompanying rain even after a week.

PM 10 had dipped to 10-15 across the air monitoring stations in the city on May 21, the day after the cyclone lashed the city, and hovered within 20-30 during the last five days, the official said.

However, the situation will change after the lockdown is lifted, environmentalists said.

"Once the lockdown is lifted and many more vehicles start plying, there will be little green cover to absorb the carbon emission and both PM 10 and PM 2.5 will rise three-four times - from good to moderate and severe category," environmentalist S M Ghosh said.

The WBPCB official said the board and the department of environment will hold a meeting with the forest department soon to decide on a large-scale tree plantation drive.

Senior West Bengal minister Partha Chatterjee recently said around 15,000 trees, "big, medium and small", were uprooted by cyclone Amphan in and around Kolkata.

However, Chairman of Board of Administrators in Kolkata Municipal Corporation, Firhad Hakim, said a total of 5,500 trees had fallen in the city under the impact of the cyclone.

During the past plantation drives, the thrust was on faster-growing trees but not on sturdier trees which can withstand high-velocity winds, Environmental activist Subhas Datta said.

Dutta, who had mooted the need for a tree census in Kolkata years back, said planting stronger trees should be considered in future.

Ghosh said instead of planting taller trees only, shorter ones like banyans should also be planted with adequate gap and not on a piece of land having underground cable lines.

Saroj Roy of the Indian Institute for Nature and Environment said, "The combined value of the felled trees would be thousands of crores of rupees, if we consider their contribution to the environment like generating oxygen and eliminating poisonous pollutants in air."